With the rack in the middle position, preheat the oven to 190 °C (375 °F).
In a roasting pan, spread the parsnips, onions, and sage. Season with salt and pepper. Set aside.
Insert the segments of one orange in the chicken’s cavity. Brush the chicken with the mustard and place over the vegetables. Drizzle with the orange juice, Triple Sec, and olive oil. Season with salt and pepper. Place the remaining orange wedges around the chicken.
Bake for about 2 hours or until a meat thermometer inserted into the thigh without touching the bone reads 82 °C (180 °F). Place the chicken and vegetables in a warm serving dish. Degrease and keep the drippings for the sauce.
In a large saucepan, combine all the ingredients and add the reserved cooking liquid. Bring to a boil, stirring with a whisk, and reduce by half. Press one or two cooked orange wedges into the sauce. Strain and adjust the seasoning. Serve with the chicken.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.